Steviol glycosides

ABSTRACT

The present invention relates to a steviol glycoside having the formula of (I)wherein at least 3 sugar moieties are present at positions R1 and at least three sugar moieties are present at position R2 and wherein the steviol glycoside comprises at least seven sugar moieties all of which are linked, directly or indirectly, to the steviol aglycon by β-linkages.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage entry of International Application No. PCT/EP2016/057360, filed 4 Apr. 2016, which claims priority to U.S. Provisional Application No. 62/142,631, filed 3 Apr. 2015.

REFERENCE TO SEQUENCE LISTING SUBMITTED AS A COMPLIANT ASCII TEXT FILE (.txt)

Pursuant to the EFS-Web legal framework and 37 CFR §§ 1.821-825 (see MPEP § 2442.03(a)), a Sequence Listing in the form of an ASCII-compliant text file (entitled “Sequence_Listing_2919208-319001_ST25.txt” created on 20 Sep. 2017, and 1,036,000 bytes in size) is submitted concurrently with the instant application, and the entire contents of the Sequence Listing are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to steviol glycosides, to methods for producing them, to sweetener compositions, flavour compositions, foodstuffs, feeds and beverages comprising the steviol glycosides and to use of the steviol glycosides in sweetener compositions, flavour compositions, foodstuffs, feeds and beverages.

BACKGROUND TO THE INVENTION

The leaves of the perennial herb, Stevia rebaudiana Bert., accumulate quantities of intensely sweet compounds known as steviol glycosides. Whilst the biological function of these compounds is unclear, they have commercial significance as alternative high potency sweeteners.

These sweet steviol glycosides have functional and sensory properties that appear to be superior to those of many high potency sweeteners. In addition, studies suggest that stevioside can reduce blood glucose levels in Type II diabetics and can reduce blood pressure in mildly hypertensive patients.

Steviol glycosides accumulate in Stevia leaves where they may comprise from 10 to 20% of the leaf dry weight. Stevioside and rebaudioside A are both heat and pH stable and suitable for use in carbonated beverages and many other foods. Stevioside is between 110 and 270 times sweeter than sucrose, rebaudioside A between 150 and 320 times sweeter than sucrose. In addition, rebaudioside D is also a high-potency diterpene glycoside sweetener which accumulates in Stevia leaves. It may be about 200 times sweeter than sucrose. Rebaudioside M is a further high-potency diterpene glycoside sweetener. It is present in trace amounts in certain stevia variety leaves, but has been suggested to have a superior taste profile.

Steviol glycosides have traditionally been extracted from the Stevia plant. In Stevia, (−)-kaurenoic acid, an intermediate in gibberellic acid (GA) biosynthesis, is converted into the tetracyclic dipterepene steviol, which then proceeds through a multi-step glycosylation pathway to form the various steviol glycosides. However, yields may be variable and affected by agriculture and environmental conditions. Also, Stevia cultivation requires substantial land area, a long time prior to harvest, intensive labour and additional costs for the extraction and purification of the glycosides.

There is though a need for additional steviol glycosides having alternative and/or improved taste profiles since different steviol glycosides may be better suited to different applications.

SUMMARY OF THE INVENTION

The present invention is based on the identification of new steviol glycosides in fermentation broths obtained from microorganisms which have been modified so as to produce steviol glycosides, including rebA. The new steviol glycosides will have different sensory properties as compared with known steviol glycosides. They may be used alone or in combination with other steviol glycosides, in particular as sweeteners or in sweetener compositions.

Accordingly, the invention relates to:

-   -   a steviol glycoside having the formula of (I)

-   -   -   wherein at least 3 sugar moieties are present at position R₁             and at least three sugar moieties are present at position R₂             and wherein the steviol glycoside comprises at least seven             sugar moieties all of which are linked, directly or             indirectly, to the steviol aglycon by β-linkages;

    -   a steviol glycoside having the formula of (I)

-   -   -   wherein at least 4 sugar moieties are present at positions             R₁ and at least three sugar moieties are present at position             R₂;

    -   a steviol glycoside having the formula of (I)

-   -   -   wherein at least 3 sugar moieties are present at position R₁             and at least three sugar moieties are present at position             R₂, wherein the steviol glycoside comprises at least seven             sugar moieties and wherein at least one of the sugars             present at position R₁ is linked to the steviol aglycon or             to a sugar molecule by a α-linkage;

    -   a steviol glycoside having the formula of (I)

-   -   -   wherein at least 3 sugar moieties are present at position R₁             and at least four sugar moieties are present at position R₂,             wherein at least four of the sugar moieties present at             position R₂ are glucose moieties;

    -   a steviol glycoside having the formula (II)

-   -   a steviol glycoside having the formula (III)

-   -   a steviol glycoside having the formula (IV)

-   -   a fermentatively produced steviol glycoside having the formula         of (I)

-   -   -   wherein at least 3 sugar moieties are present at position R₁             and at least three sugar moieties are present at position R₂             and wherein the steviol glycoside comprises at least seven             sugar moieties;

    -   a method for the production of a steviol glycoside according to         any one of the preceding claims, which method comprises:         -   providing a recombinant yeast cell comprising recombinant             nucleic acid sequences encoding polypeptides comprising the             amino acid sequences encoded by: SEQ ID NO: 61, SEQ ID NO:             65, SEQ ID NO: 23, SEQ ID NO: 33, SEQ ID NO: 77, SEQ ID NO:             71, SEQ ID NO: 87, SEQ ID NO: 73 and SEQ ID NO: 75;         -   fermenting the recombinant yeast cell in a suitable             fermentation medium; and, optionally,         -   recovering a steviol glycoside according to any one of the             preceding claims.

    -   a composition comprising a steviol glycoside of the invention         and one or more different steviol glycosides (which different         steviol glycosides may or may not be a steviol glycoside of the         invention);

    -   a sweetener composition, flavor composition, foodstuff, feed or         beverage which comprises a steviol glycoside or a composition of         the invention;

    -   use of a steviol glycoside or a composition of the invention in         a sweetener composition or flavor composition; and

    -   use of a steviol glycoside or a composition of the invention in         a foodstuff, feed or beverage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 sets out a schematic representation of the plasmid pUG7-EcoRV.

FIG. 2 sets out a schematic representation of the method by which the ERG20, tHMG1 and BTS1 over-expression cassettes are designed (A) and integrated (B) into the yeast genome. (C) shows the final situation after removal of the KANMX marker by the Cre recombinase.

FIG. 3 sets out a schematic representation of the ERG9 knock down construct. This consists of a 500 bp long 3′ part of ERG9, 98 bp of the TRP1 promoter, the TRP1 open reading frame and terminator, followed by a 400 bp long downstream sequence of ERG9. Due to introduction of a XbaI site at the end of the ERG9 open reading frame the last amino acid changes into Ser and the stop codon into Arg. A new stop codon is located in the TPR1 promoter, resulting in an extension of 18 amino acids.

FIG. 4 sets out a schematic representation of how UGT2 is integrated into the genome. A. different fragments used in transformation; B. situation after integration; C. situation after expression of Cre recombinase).

FIG. 5 sets out a schematic representation of how the pathway from GGPP to RebA is integrated into the genome. A. different fragments used in transformation; B. situation after integration.

FIG. 6a shows an extracted ion chromatogram of m/z 1451.5820 of the mixture of the steviol glycosides containing 7 glucoses (7.1, 7.2 and 7.3) in the ethanol extract (starting material for purification), using High Resolution Mass Spectrometry; and FIG. 6b : extracted ion chromatogram of m/z 1451.5 of the purified steviol glycosides containing 7 glucoses (7.1, 7.2 and 7.3), using LC-MS.

FIG. 7 shows the structure of Rebaudioside 7.1.

FIG. 8 shows the structure of Rebaudioside 7.2.

FIG. 9 shows the structure of Rebaudioside 7.3.

FIG. 10 shows the structure of Rebaudioside M.

FIG. 11A shows atom numbering of steviol, and FIG. 11B shows atom numbering of glucose.

FIG. 12 shows the selected region of the 1H NMR spectrum of a) Reb M (cdcl3/pyr 1:1, 2 drops cdood at 300K), b) Reb 7.1 (cdcl3/pyr 1:3, 2 drops cdood at 320K) c) Reb 7.2 (cdcl3/pyr 1:1, 2 drops cdood at 300K) and d) Reb 7.3 (cdcl3/pyr 1:2, 3 drops cdood at 300K).

DESCRIPTION OF THE SEQUENCE LISTING

A description of the sequences is set out in Table 15. Sequences described herein may be defined with reference to the sequence listing or with reference to the database accession numbers also set out in Table 15.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the present specification and the accompanying claims, the words “comprise”, “include” and “having” and variations such as “comprises”, “comprising”, “includes” and “including” are to be interpreted inclusively. That is, these words are intended to convey the possible inclusion of other elements or integers not specifically recited, where the context allows.

The articles “a” and “an” are used herein to refer to one or to more than one (i.e. to one or at least one) of the grammatical object of the article. By way of example, “an element” may mean one element or more than one element.

This invention relates to steviol glycosides. For the purposes of this invention, a steviol glycosides is a glycoside of steviol, specifically a steviol molecule with its carboxyl hydrogen atom replaced by a glucose molecule to form an ester, and an hydroxyl hydrogen with glucose to form an acetal.

A steviol glycoside of the invention may be provided in isolated form. An “isolated steviol glycoside” is a substance removed from other material, such as other steviol glycosides, with which it may be naturally associated. Thus, an isolated steviol glycoside may contain at most 10%, at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, even more preferably at most 1% and most preferably at most 0.5% by weight of other material, for example other steviol glycosides, with which it is naturally associated. The isolated steviol glycosides may be free of any other impurities. The isolated steviol glycoside of the invention may be at least 50% pure, e.g., at least 60% pure, at least 70% pure, at least 75% pure, at least 80% pure, at least 85% pure, at least 90% pure, or at least 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9% pure by weight.

The invention provides a steviol glycoside having the formula of (I)

-   -   wherein at least 3 sugar moieties are present at position R₁ and         at least three sugar moieties are present at position R₂ and         wherein the steviol glycoside comprises at least seven sugar         moieties all of which are linked, directly or indirectly, to the         steviol aglycon by β-linkages, or     -   wherein at least 4 sugar moieties are present at positions R₁         and at least three sugar moieties are present at position R₂, or     -   wherein at least 3 sugar moieties are present at position R₁ and         at least three sugar moieties are present at position R₂,         wherein the steviol glycoside comprises at least seven sugar         moieties and wherein at least one of the sugars present at         position R₁ is linked to the steviol aglycon or to a sugar         molecule by a α-linkage, or     -   wherein at least 3 sugar moieties are present at position R₁ and         at least four sugar moieties are present at position R₂, wherein         at least four of the sugar moieties present at position R₂ are         glucose moieties.

The invention also provides steviol glycosides having the formula (II), (Ill) or (IV):

A steviol glycoside of the invention may be obtained from plant material, but more typically will be obtained by fermentative production, for example via fermentation of a recombinant host cell, such as a yeast cell.

Thus, the invention provides a fermentatively produced steviol glycoside having the formula of (I)

-   -   wherein at least 3 sugar moieties are present at position R₁ and         at least three sugar moieties are present at position R₂ and         wherein the steviol glycoside comprises at least seven sugar         moieties.

One may distinguish between α- and β-glycosidic bonds based on the relative stereochemistry (R or S) of the anomeric position and the stereocentre furthest from C1 in a saccharide. Typically, an α-glycosidic bond is formed when both carbons have the same stereochemistry, whereas a β-glycosidic bond occurs when the two carbons have different stereochemistry

Such a fermentatively-produced steviol glycoside may have a structure of any of the steviol glycosides described herein.

The invention further relates to a method for the production of a steviol glycoside. In such a method, a suitable recombinant host cell, such as a yeast cell, is fermented in a suitable fermentation medium such that the steviol glycoside is produced. Optionally, the steviol glycoside may be recovered.

For example, a method for the production of a steviol glycoside as described herein may comprise:

providing a recombinant yeast cell comprising recombinant nucleic acid sequences encoding polypeptides comprising the amino acid sequences encoded by: SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 23, SEQ ID NO: 33, SEQ ID NO: 77, SEQ ID NO: 71, SEQ ID NO: 87, SEQ ID NO: 73 and SEQ ID NO: 75;

fermenting the recombinant yeast cell in a suitable fermentation medium; and, optionally,

recovering a steviol glycoside as described herein.

The term “recombinant” when used in reference to a cell, nucleic acid, protein or vector, indicates that the cell, nucleic acid, protein or vector, has been modified by the introduction of a heterologous nucleic acid or protein or the alteration of a native nucleic acid or protein, or that the cell is derived from a cell so modified. Thus, for example, recombinant cells express genes that are not found within the native (non-recombinant) form of the cell or express native genes that are otherwise abnormally expressed, under expressed or not expressed at all. The term “recombinant” is synonymous with “genetically modified”.

A recombinant yeast cell used in a process of the invention may be any suitable yeast cell. Preferred recombinant yeast cells may be selected from the genera: Saccharomyces (e.g., S. cerevisiae, S. bayanus, S. pastorianus, S. carlsbergensis), Brettanomyces, Kluyveromyces, Candida (e.g., C. krusei, C. revkaufi, C. pulcherrima, C. tropicalis, C. utilis), Issatchenkia (eg. I. orientalis) Pichia (e.g., P. pastoris), Schizosaccharomyces, Hansenula, Kloeckera, Pachysolen, Schwanniomyces, Trichosporon, Yarrowia (e.g., Y. lipolytica (formerly classified as Candida lipolytica)) or Yamadazyma. Preferably, the recombinant yeast cell is a Saccharomyces cerevisiae, Yarrowia lipolitica or Issatchenkia orientalis cell.

A recombinant yeast cell for use in a method according to the invention may comprise one or more recombinant nucleotide sequence(s) encoding one of more of:

a polypeptide having ent-copalyl pyrophosphate synthase activity;

a polypeptide having ent-Kaurene synthase activity;

a polypeptide having ent-Kaurene oxidase activity; and

a polypeptide having kaurenoic acid 13-hydroxylase activity.

For the purposes of this invention, a polypeptide having ent-copalyl pyrophosphate synthase (EC 5.5.1.13) is capable of catalyzing the chemical reation:

This enzyme has one substrate, geranylgeranyl pyrophosphate, and one product, ent-copalyl pyrophosphate. This enzyme participates in gibberellin biosynthesis. This enzyme belongs to the family of isomerase, specifically the class of intramolecular lyases. The systematic name of this enzyme class is ent-copalyl-diphosphate lyase (decyclizing). Other names in common use include having ent-copalyl pyrophosphate synthase, ent-kaurene synthase A, and ent-kaurene synthetase A.

Suitable nucleic acid sequences encoding an ent-copalyl pyrophosphate synthase may for instance comprise a sequence as set out in SEQ ID. NO: 1, 3, 5, 7, 17, 19, 59, 61, 141, 142, 151, 152, 153, 154, 159, 160, 182 or 184.

For the purposes of this invention, a polypeptide having ent-kaurene synthase activity (EC 4.2.3.19) is a polypeptide that is capable of catalyzing the chemical reaction: ent-copalyl diphosphate

ent-kaurene+diphosphate

Hence, this enzyme has one substrate, ent-copalyl diphosphate, and two products, ent-kaurene and diphosphate.

This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is ent-copalyl-diphosphate diphosphate-lyase (cyclizing, ent-kaurene-forming). Other names in common use include ent-kaurene synthase B, ent-kaurene synthetase B, ent-copalyl-diphosphate diphosphate-lyase, and (cyclizing). This enzyme participates in diterpenoid biosynthesis.

Suitable nucleic acid sequences encoding an ent-Kaurene synthase may for instance comprise a sequence as set out in SEQ ID. NO: 9, 11, 13, 15, 17, 19, 63, 65, 143, 144, 155, 156, 157, 158, 159, 160, 183 or 184.

ent-copalyl diphosphate synthases may also have a distinct ent-kaurene synthase activity associated with the same protein molecule. The reaction catalyzed by ent-kaurene synthase is the next step in the biosynthetic pathway to gibberellins. The two types of enzymic activity are distinct, and site-directed mutagenesis to suppress the ent-kaurene synthase activity of the protein leads to build up of ent-copalyl pyrophosphate.

Accordingly, a single nucleotide sequence used in a recombinant yeast suitable for use in the method of the invention may encode a polypeptide having ent-copalyl pyrophosphate synthase activity and ent-kaurene synthase activity. Alternatively, the two activities may be encoded two distinct, separate nucleotide sequences.

For the purposes of this invention, a polypeptide having ent-kaurene oxidase activity (EC 1.14.13.78) is a polypeptide which is capable of catalysing three successive oxidations of the 4-methyl group of ent-kaurene to give kaurenoic acid. Such activity typically requires the presence of a cytochrome P450.

Suitable nucleic acid sequences encoding an ent-Kaurene oxidase may for instance comprise a sequence as set out in SEQ ID. NO: 21, 23, 25, 67, 85, 145, 161, 162, 163, 180 or 186.

For the purposes of the invention, a polypeptide having kaurenoic acid 13-hydroxylase activity (EC 1.14.13) is one which is capable of catalyzing the formation of steviol (ent-kaur-16-en-13-ol-19-oic acid) using NADPH and O₂. Such activity may also be referred to as ent-ka 13-hydroxylase activity.

Suitable nucleic acid sequences encoding a kaurenoic acid 13-hydroxylase may for instance comprise a sequence as set out in SEQ ID. NO: 27, 29, 31, 33, 69, 89, 91, 93, 95, 97, 146, 164, 165, 166, 167 or 185.

A recombinant yeast cell suitable for use in the method of the invention may comprise a recombinant nucleic acid sequence encoding a polypeptide having NADPH-cytochrome p450 reductase activity. That is to say, a recombinant yeast suitable for use in a method of the invention may be capable of expressing a nucleotide sequence encoding a polypeptide having NADPH-cytochrome p450 reductase activity. For the purposes of the invention, a polypeptide having NADPH-Cytochrome P450 reductase activity (EC 1.6.2.4; also known as NADPH:ferrihemoprotein oxidoreductase, NADPH:hemoprotein oxidoreductase, NADPH:P450 oxidoreductase, P450 reductase, POR, CPR, CYPOR) is typically one which is a membrane-bound enzyme allowing electron transfer to cytochrome P450 in the microsome of the eukaryotic cell from a FAD- and FMN-containing enzyme NADPH:cytochrome P450 reductase (POR; EC 1.6.2.4).

Suitable nucleic acid sequences encoding a NADPH-cytochrome p450 reductase may for instance comprise a sequence as set out in SEQ ID. NO: 53, 55, 57 or 77.

A recombinant yeast cell suitable for use in a method of the invention may also comprise one or more recombinant nucleic acid sequences encoding one or more of:

(i) a polypeptide having UGT74G1 activity;

(ii) a polypeptide having UGT2 activity;

(iii) a polypeptide having UGT85C2 activity; and

(iv) a polypeptide having UGT76G1 activity.

A recombinant yeast suitable for use in the invention may comprise a nucleotide sequence encoding a polypeptide capable of catalyzing the addition of a C-13-glucose to steviol. That is to say, a recombinant yeast suitable for use in a method of the invention may comprise a UGT which is capable of catalyzing a reaction in which steviol is converted to steviolmonoside.

Such a recombinant yeast suitable for use in a method of the invention may comprise a nucleotide sequence encoding a polypeptide having the activity shown by UDP-glycosyltransferase (UGT) UGT85C2, whereby the nucleotide sequence upon transformation of the yeast confers on that yeast the ability to convert steviol to steviolmonoside.

UGT85C2 activity is transfer of a glucose unit to the 13-OH of steviol. Thus, a suitable UGT85C2 may function as a uridine 5′-diphospho glucosyl: steviol 13-OH transferase, and a uridine 5′-diphospho glucosyl: steviol-19-0-glucoside 13-OH transferase. A functional UGT85C2 polypeptides may also catalyze glucosyl transferase reactions that utilize steviol glycoside substrates other than steviol and steviol-19-O-glucoside. Such sequences may be referred to as UGT1 sequences herein.

A recombinant yeast suitable for use in the invention may comprise a nucleotide sequence encoding a polypeptide which has UGT2 activity.

A polypeptide having UGT2 activity is one which functions as a uridine 5′-diphospho glucosyl: steviol-13-O-glucoside transferase (also referred to as a steviol-13-monoglucoside 1,2-glucosylase), transferring a glucose moiety to the C-2′ of the 13-O-glucose of the acceptor molecule, steviol-13-O-glucoside. Typically, a suitable UGT2 polypeptide also functions as a uridine 5′-diphospho glucosyl: rubusoside transferase transferring a glucose moiety to the C-2′ of the 13-O-glucose of the acceptor molecule, rubusoside.

A polypeptide having UGT2 activity may also catalyze reactions that utilize steviol glycoside substrates other than steviol-13-0-glucoside and rubusoside, e.g., functional UGT2 polypeptides may utilize stevioside as a substrate, transferring a glucose moiety to the C-2′ of the 19-O-glucose residue to produce rebaudioside E. A functional UGT2 polypeptides may also utilize rebaudioside A as a substrate, transferring a glucose moiety to the C-2′ of the 19-O-glucose residue to produce rebaudioside D. However, a functional UGT2 polypeptide typically does not transfer a glucose moiety to steviol compounds having a 1,3-bound glucose at the C-13 position, i.e., transfer of a glucose moiety to steviol 1,3-bioside and 1,3-stevioside typically does not occur.

A polypeptide having UGT2 activity may also transfer sugar moieties from donors other than uridine diphosphate glucose. For example, a polypeptide having UGT2 activity act as a uridine 5′-diphospho D-xylosyl: steviol-13-O-glucoside transferase, transferring a xylose moiety to the C-2′ of the 13-O-glucose of the acceptor molecule, steviol-13-O-glucoside. As another example, a polypeptide having UGT2 activity may act as a uridine 5′-diphospho L-rhamnosyl: steviol-13-0-glucoside transferase, transferring a rhamnose moiety to the C-2′ of the 13-O-glucose of the acceptor molecule, steviol.

A recombinant yeast suitable for use in the method of the invention may comprise a nucleotide sequence encoding a polypeptide having UGT activity may comprise a nucleotide sequence encoding a polypeptide capable of catalyzing the addition of a C-19-glucose to steviolbioside. That is to say, a recombinant yeast of the invention may comprise a UGT which is capable of catalyzing a reaction in which steviolbioside is converted to stevioside. Accordingly, such a recombinant yeast may be capable of converting steviolbioside to stevioside. Expression of such a nucleotide sequence may confer on the recombinant yeast the ability to produce at least stevioside.

A recombinant yeast suitable for use in a method of the invention may thus also comprise a nucleotide sequence encoding a polypeptide having the activity shown by UDP-glycosyltransferase (UGT) UGT74G1, whereby the nucleotide sequence upon transformation of the yeast confers on the cell the ability to convert steviolbioside to stevioside.

Suitable UGT74G1 polypeptides may be capable of transferring a glucose unit to the 13-OH or the 19-COOH, respectively, of steviol. A suitable UGT74G1 polypeptide may function as a uridine 5′-diphospho glucosyl: steviol 19-COOH transferase and a uridine 5′-diphospho glucosyl: steviol-13-O-glucoside 19-COOH transferase. Functional UGT74G1 polypeptides also may catalyze glycosyl transferase reactions that utilize steviol glycoside substrates other than steviol and steviol-13-O-glucoside, or that transfer sugar moieties from donors other than uridine diphosphate glucose. Such sequences may be referred to herein as UGT3 sequences.

A recombinant yeast suitable for use in a method the invention may comprise a nucleotide sequence encoding a polypeptide capable of catalyzing glucosylation of the C-3′ of the glucose at the C-13 position of stevioside. That is to say, a recombinant yeast suitable for use in a method of the invention may comprise a UGT which is capable of catalyzing a reaction in which stevioside is converted to rebaudioside A. Accordingly, such a recombinant yeast may be capable of converting stevioside to rebaudioside A. Expression of such a nucleotide sequence may confer on the yeast the ability to produce at least rebaudioside A.

A recombinant yeast suitable for use in a method of the invention may thus also comprise a nucleotide sequence encoding a polypeptide having the activity shown by UDP-glycosyltransferase (UGT) UGT76G1, whereby the nucleotide sequence upon transformation of a yeast confers on that yeast the ability to convert stevioside to rebaudioside A.

A suitable UGT76G1 adds a glucose moiety to the C-3′ of the C-13-O-glucose of the acceptor molecule, a steviol 1,2 glycoside. Thus, UGT76G1 functions, for example, as a uridine 5′-diphospho glucosyl: steviol 13-0-1,2 glucoside C-3′ glucosyl transferase and a uridine 5′-diphospho glucosyl: steviol-19-0-glucose, 13-0-1,2 bioside C-3′ glucosyl transferase. Functional UGT76G1 polypeptides may also catalyze glucosyl transferase reactions that utilize steviol glycoside substrates that contain sugars other than glucose, e.g., steviol rhamnosides and steviol xylosides. Such sequences may be referred to herein as UGT4 sequences. A UGT4 may alternatively or in addition be capable of converting RebD to RebM.

A recombinant yeast suitable for use in a method of the invention typically comprises nucleotide sequences encoding at least one polypeptide having UGT1 activity, at least one polypeptide having UGT2 activity, least one polypeptide having UGT3 activity and at least one polypeptide having UGT4 activity. One or more of these nucleic acid sequences may be recombinant. A given nucleic acid may encode a polypeptide having one or more of the above activities. For example, a nucleic acid encode for a polypeptide which has two, three or four of the activities set out above. Preferably, a recombinant yeast for use in the method of the invention comprises UGT1, UGT2 and UGT3 and UGT4 activity. Suitable UGT1, UGT2, UGT3 and UGT4 sequences are described in in Table 15 herein. A preferred combination of sequences encoding UGT1, 2, 3 and 4 activities is SEQ ID NOs: 71, 87, 73 and 75.

In the method of the invention, a recombinant host, such as a yeast, may be able to grow on any suitable carbon source known in the art and convert it to one or more steviol glycosides. The recombinant host may be able to convert directly plant biomass, celluloses, hemicelluloses, pectines, rhamnose, galactose, fucose, maltose, maltodextrines, ribose, ribulose, or starch, starch derivatives, sucrose, lactose and glycerol. Hence, a preferred host expresses enzymes such as cellulases (endocellulases and exocellulases) and hemicellulases (e.g. endo- and exo-xylanases, arabinases) necessary for the conversion of cellulose into glucose monomers and hemicellulose into xylose and arabinose monomers, pectinases able to convert pectines into glucuronic acid and galacturonic acid or amylases to convert starch into glucose monomers. Preferably, the host is able to convert a carbon source selected from the group consisting of glucose, xylose, arabinose, sucrose, lactose and glycerol. The host cell may for instance be a eukaryotic host cell as described in WO03/062430, WO06/009434, EP149970861, WO2006096130 or WO04/099381.

The fermentation medium used in the process for the production of a steviol glycoside of the invention may be any suitable fermentation medium which allows growth of a particular eukaryotic host cell. The essential elements of the fermentation medium are known to the person skilled in the art and may be adapted to the host cell selected.

Preferably, the fermentation medium comprises a carbon source selected from the group consisting of plant biomass, celluloses, hemicelluloses, pectines, rhamnose, galactose, fucose, fructose, maltose, maltodextrines, ribose, ribulose, or starch, starch derivatives, sucrose, lactose, fatty acids, triglycerides and glycerol. Preferably, the fermentation medium also comprises a nitrogen source such as ureum, or an ammonium salt such as ammonium sulphate, ammonium chloride, ammoniumnitrate or ammonium phosphate.

The fermentation process according to the present invention may be carried out in batch, fed-batch or continuous mode. A separate hydrolysis and fermentation (SHF) process or a simultaneous saccharification and fermentation (SSF) process may also be applied. A combination of these fermentation process modes may also be possible for optimal productivity. A SSF process may be particularly attractive if starch, cellulose, hemicelluose or pectin is used as a carbon source in the fermentation process, where it may be necessary to add hydrolytic enzymes, such as cellulases, hemicellulases or pectinases to hydrolyse the substrate.

The fermentation process for the production of a steviol glycoside according to the present invention may be an aerobic or an anaerobic fermentation process.

An anaerobic fermentation process may be herein defined as a fermentation process run in the absence of oxygen or in which substantially no oxygen is consumed, preferably less than 5, 2.5 or 1 mmol/L/h, and wherein organic molecules serve as both electron donor and electron acceptors. The fermentation process according to the present invention may also first be run under aerobic conditions and subsequently under anaerobic conditions.

The fermentation process may also be run under oxygen-limited, or micro-aerobical, conditions. Alternatively, the fermentation process may first be run under aerobic conditions and subsequently under oxygen-limited conditions. An oxygen-limited fermentation process is a process in which the oxygen consumption is limited by the oxygen transfer from the gas to the liquid. The degree of oxygen limitation is determined by the amount and composition of the ingoing gas flow as well as the actual mixing/mass transfer properties of the fermentation equipment used.

The production of a steviol glycoside in the process according to the present invention may occur during the growth phase of the host cell, during the stationary (steady state) phase or during both phases. It may be possible to run the fermentation process at different temperatures.

The process for the production of a steviol glycoside may be run at a temperature which is optimal for the recombinant host. The optimum growth temperature may differ for each transformed recombinant host and is known to the person skilled in the art. The optimum temperature might be higher than optimal for wild type organisms to grow the organism efficiently under non-sterile conditions under minimal infection sensitivity and lowest cooling cost. Alternatively, the process may be carried out at a temperature which is not optimal for growth of the recombinant host.

The process for the production of a steviol glycoside according to the present invention may be carried out at any suitable pH value. If the recombinant host is a yeast, the pH in the fermentation medium preferably has a value of below 6, preferably below 5.5, preferably below 5, preferably below 4.5, preferably below 4, preferably below pH 3.5 or below pH 3.0, or below pH 2.5, preferably above pH 2. An advantage of carrying out the fermentation at these low pH values is that growth of contaminant bacteria in the fermentation medium may be prevented.

Such a process may be carried out on an industrial scale. The product of such a process is one or more steviol glycosides according to the invention.

Recovery of steviol glycoside(s) of the invention from the fermentation medium may be performed by known methods in the art, for instance by distillation, vacuum extraction, solvent extraction, or evaporation.

In the process for the production of a steviol glycoside according to the invention, it may be possible to achieve a concentration of above 0.5 mg/I, preferably above about 1 mg/I.

In the event that one or more steviol glycosides of the invention is expressed within a recombinant host, such cells may need to be treated so as to release them.

The invention also provides a composition comprising a steviol glycoside of the invention in combination with one or more different steviol glycosides. One or more of the one or more different steviol glycosides may be a steviol glycoside of the invention. One or more of the one or more different steviol glycosides may be a glycosylated diterpene (i.e. a diterpene glycoside), such as steviolmonoside, steviolbioside, stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside E, rebaudioside F, rebaudioside M, rubusoside, dulcoside A, steviol-13-monoside, steviol-19-monoside or 13-[(β-D-Glucopyranosyl)oxy)kaur-16-en-18-oic acid 2-O-β-D-glucopyranosyl-p-D-glucopyranosyl ester.

A composition of the invention may comprise a relatively low amount of a steviol glycoside of the invention in combination with a greater amount of a different steviol glycoside.

For example, a composition of the invention may comprise at least about 80%, at least about 90%, at least about 95% rebaudioside A in combination with a steviol glycoside of the invention. A composition of the invention may comprise at least about 80%, at least about 90%, at least about 95% rebaudioside D in combination with a steviol glycoside of the invention. A composition of the invention may comprise at least about 80%, at least about 90%, at least about 95% rebaudioside M in combination with a steviol glycoside of the invention. A composition of the invention may comprise at least about 80%, at least about 90%, at least about 95% rebaudioside A in combination with a steviol glycoside of the invention and rebaudioside D. A composition of the invention may comprise at least about 80%, at least about 90%, at least about 95% rebaudioside A in combination with a steviol glycoside of the invention and rebaudioside M. Percentages referred to are on a dry weight basis.

A steviol glycoside according to the present invention may be used in any application known for such compounds. In particular, they may for instance be used as a sweetener or flavour, for example, in a food, feed or a beverage. For example steviol glycosides may be formulated in soft drinks such as carbonated beverages, as a tabletop sweetener, chewing gum, dairy product such as yoghurt (eg. plain yoghurt), cake, cereal or cereal-based food, nutraceutical, pharmaceutical, edible gel, confectionery product, cosmetic, toothpastes or other oral cavity composition, etc. In addition, a steviol glycoside can be used as a sweetener not only for drinks, foodstuffs, and other products dedicated for human consumption, but also in animal feed and fodder with improved characteristics.

Accordingly, the invention provides, inter alia, a sweetener composition, a flavor composition, a foodstuff, feed or beverage which comprises a steviol gylcoside prepared according to a process of the invention.

A composition of the invention may comprise one or more non-naturally occurring components.

Furthermore, the invention provides:

-   -   use of a steviol glycoside or a composition of the invention in         a sweetener composition or flavor composition; and     -   use of a steviol glycoside or a composition of the invention in         a foodstuff, feed or beverage.

During the manufacturing of foodstuffs, drinks, pharmaceuticals, cosmetics, table top products, chewing gum the conventional methods such as mixing, kneading, dissolution, pickling, permeation, percolation, sprinkling, atomizing, infusing and other methods can be used.

The steviol glycoside obtained in this invention can be used in dry or liquid forms. It can be added before or after heat treatment of food products. The amount of the sweetener depends on the purpose of usage. It can be added alone or in the combination with other compounds.

Compounds produced according to the method of the invention may be blended with one or more further non-calorific or calorific sweeteners. Such blending may be used to improve flavour or temporal profile or stability. The steviol glycoside of the invention may be used to improve the flavour or temporal profile or stability of a second steviol glycoside, such as rebaudiose A, D or M.

A wide range of both non-calorific and calorific sweeteners may be suitable for blending with a steviol glycoside of the invention, including one or more other steviol glycosides according to the invention or one or more other known steviol glycosides such as steviolmonoside, steviolbioside, stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside E, rebaudioside F, rebaudioside M, rubusoside, dulcoside A, steviol-13-monoside, steviol-19-monoside or 13-[(β-D-Glucopyranosyl)oxy)kaur-16-en-18-oic acid 2-O-β-D-glucopyranosyl-β-D-glucopyranosyl ester. Alternatively, or in addition, non-calorific sweeteners such as mogroside, monatin, aspartame, acesulfame salts, cyclamate, sucralose, saccharin salts or erythritol. Calorific sweeteners suitable for blending with steviol glycosides include sugar alcohols and carbohydrates such as sucrose, glucose, fructose and HFCS. Sweet tasting amino acids such as glycine, alanine or serine may also be used.

The steviol glycoside can be used in the combination with a sweetener suppressor, such as a natural sweetener suppressor. It may be combined with an umami taste enhancer, such as an amino acid or a salt thereof.

A steviol glycoside can be combined with a polyol or sugar alcohol, a carbohydrate, a physiologically active substance or functional ingredient (for example a carotenoid, dietary fiber, fatty acid, saponin, antioxidant, nutraceutical, flavonoid, isothiocyanate, phenol, plant sterol or stanol (phytosterols and phytostanols), a polyols, a prebiotic, a probiotic, a phytoestrogen, soy protein, sulfides/thiols, amino acids, a protein, a vitamin, a mineral, and/or a substance classified based on a health benefits, such as cardiovascular, cholesterol-reducing or anti-inflammatory.

A composition with a steviol glycoside may include a flavoring agent, an aroma component, a nucleotide, an organic acid, an organic acid salt, an inorganic acid, a bitter compound, a protein or protein hydrolyzate, a surfactant, a flavonoid, an astringent compound, a vitamin, a dietary fiber, an antioxidant, a fatty acid and/or a salt.

A steviol glycoside of the invention may be applied as a high intensity sweetener to produce zero calorie, reduced calorie or diabetic beverages and food products with improved taste characteristics. Also it can be used in drinks, foodstuffs, pharmaceuticals, and other products in which sugar cannot be used.

In addition, a steviol glycoside of the invention may be used as a sweetener not only for drinks, foodstuffs, and other products dedicated for human consumption, but also in animal feed and fodder with improved characteristics.

The examples of products where a steviol glycoside of the invention composition can be used as a sweetening compound can be as alcoholic beverages such as vodka, wine, beer, liquor, sake, etc; natural juices, refreshing drinks, carbonated soft drinks, diet drinks, zero calorie drinks, reduced calorie drinks and foods, yogurt drinks, instant juices, instant coffee, powdered types of instant beverages, canned products, syrups, fermented soybean paste, soy sauce, vinegar, dressings, mayonnaise, ketchups, curry, soup, instant bouillon, powdered soy sauce, powdered vinegar, types of biscuits, rice biscuit, crackers, bread, chocolates, caramel, candy, chewing gum, jelly, pudding, preserved fruits and vegetables, fresh cream, jam, marmalade, flower paste, powdered milk, ice cream, sorbet, vegetables and fruits packed in bottles, canned and boiled beans, meat and foods boiled in sweetened sauce, agricultural vegetable food products, seafood, ham, sausage, fish ham, fish sausage, fish paste, deep fried fish products, dried seafood products, frozen food products, preserved seaweed, preserved meat, tobacco, medicinal products, and many others. In principal it can have unlimited applications.

The sweetened composition comprises a beverage, non-limiting examples of which include non-carbonated and carbonated beverages such as colas, ginger ales, root beers, ciders, fruit-flavored soft drinks (e.g., citrus-flavored soft drinks such as lemon-lime or orange), powdered soft drinks, and the like; fruit juices originating in fruits or vegetables, fruit juices including squeezed juices or the like, fruit juices containing fruit particles, fruit beverages, fruit juice beverages, beverages containing fruit juices, beverages with fruit flavorings, vegetable juices, juices containing vegetables, and mixed juices containing fruits and vegetables; sport drinks, energy drinks, near water and the like drinks (e.g., water with natural or synthetic flavorants); tea type or favorite type beverages such as coffee, cocoa, black tea, green tea, oolong tea and the like; beverages containing milk components such as milk beverages, coffee containing milk components, cafe au lait, milk tea, fruit milk beverages, drinkable yogurt, lactic acid bacteria beverages or the like; and dairy products.

Generally, the amount of sweetener present in a sweetened composition varies widely depending on the particular type of sweetened composition and its desired sweetness. Those of ordinary skill in the art can readily discern the appropriate amount of sweetener to put in the sweetened composition.

The steviol glycoside of the invention can be used in dry or liquid forms. It can be added before or after heat treatment of food products. The amount of the sweetener depends on the purpose of usage. It can be added alone or in the combination with other compounds.

During the manufacturing of foodstuffs, drinks, pharmaceuticals, cosmetics, table top products, chewing gum the conventional methods such as mixing, kneading, dissolution, pickling, permeation, percolation, sprinkling, atomizing, infusing and other methods can be used.

Thus, compositions of the present invention can be made by any method known to those skilled in the art that provide homogenous even or homogeneous mixtures of the ingredients. These methods include dry blending, spray drying, agglomeration, wet granulation, compaction, co-crystallization and the like.

In solid form a steviol glycoside of the invention of the present invention can be provided to consumers in any form suitable for delivery into the comestible to be sweetened, including sachets, packets, bulk bags or boxes, cubes, tablets, mists, or dissolvable strips. The composition can be delivered as a unit dose or in bulk form.

For liquid sweetener systems and compositions convenient ranges of fluid, semi-fluid, paste and cream forms, appropriate packing using appropriate packing material in any shape or form shall be invented which is convenient to carry or dispense or store or transport any combination containing any of the above sweetener products or combination of product produced above.

The composition may include various bulking agents, functional ingredients, colorants, flavors.

Standard genetic techniques, such as overexpression of enzymes in the host cells, genetic modification of host cells, or hybridisation techniques, are known methods in the art, such as described in Sambrook and Russel (2001) “Molecular Cloning: A Laboratory Manual (3^(rd) edition), Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, or F. Ausubel et al, eds., “Current protocols in molecular biology”, Green Publishing and Wiley Interscience, New York (1987). Methods for transformation, genetic modification etc of fungal host cells are known from e.g. EP-A-0 635 574, WO 98/46772, WO 99/60102 and WO 00/37671, WO90/14423, EP-A-0481008, EP-A-0635 574 and U.S. Pat. No. 6,265,186.

Embodiments of the Invention

-   1. A steviol glycoside having the formula of (I)

wherein at least 3 sugar moieties are present at positions R₁ and at least three sugar moieties are present at position R₂ and wherein the steviol glycoside comprises at least seven sugar moieties all of which are linked, directly or indirectly, to the steviol aglycon by β-linkages.

-   2. A steviol glycoside having the formula of (I)

wherein at least 4 sugar moieties are present at positions R₁ and at least three sugar moieties are present at position R₂.

-   3. A steviol glycoside having the formula of (I)

wherein at least 3 sugar moieties are present at positions R₁ and at least three sugar moieties are present at position R₂, wherein the steviol glycoside comprises at least seven sugar moieties and wherein at least one of the sugars present at position R₁ is linked to the steviol aglycon or to a sugar molecule by a α-linkage.

-   4. A steviol glycoside having the formula of (I)

wherein at least 3 sugar moieties are present at positions R₁ and at least four sugar moieties are present at position R₂, wherein at least four of the sugar moieties present at position R₂ are glucose moieties.

-   5. A steviol glycoside having the formula (II)

-   6. A steviol glycoside having the formula (III)

-   7. A steviol glycoside having the formula (IV)

-   8. A steviol glycoside according to any one of the preceding     embodiments which is fermentatively produced. -   9. A fermentatively produced steviol glycoside having the formula of     (I)

wherein at least 3 sugar moieties are present at positions R₁ and at least three sugar moieties are present at position R₂ and wherein the steviol glycoside comprises at least seven sugar moieties.

-   10. A steviol glycoside according to embodiment 9 having a structure     according to any one of embodiments 1 to 7. -   11. A method for the production of a steviol glycoside according to     any one of the preceding embodiments, which method comprises:

providing a recombinant yeast cell comprising recombinant nucleic acid sequences encoding polypeptides comprising the amino acid sequences encoded by: SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 23, SEQ ID NO: 33, SEQ ID NO: 59, SEQ ID NO: 71, SEQ ID NO: 87, SEQ ID NO: 73 and SEQ ID NO: 75;

fermenting the recombinant yeast cell in a suitable fermentation medium; and, optionally,

recovering a steviol glycoside according to any one of the preceding embodiments.

-   12. A composition comprising a steviol glycoside according to any     one of embodiments 1 to 11 and one or more different steviol     glycosides. -   13. A foodstuff, feed or beverage which comprises a steviol     glycoside according to any one of embodiments 1 to 10 or a     composition according to embodiment 12. -   14. Use of a steviol glycoside according to any one of embodiments 1     to 10 or a composition according to embodiment 12 in a sweetener     composition or flavor composition. -   15. Use of a steviol glycoside according to any one of embodiment 1     to 10 or a composition according to embodiment 12 in a foodstuff,     feed or beverage.

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

The disclosure of each reference set forth herein is incorporated herein by reference in its entirety.

The present invention is further illustrated by the following Examples:

EXAMPLES Example 1 Construction of STV016

S. cerevisiae Strain STV016 was constructed for the fermentative production of steviol glycosides.

1.1 Over-Expression of ERG20, BTS1 and tHMG in S. cerevisiae

For over-expression of ERG20, BTS1 tHMG1, expression cassettes were designed to be integrated in one locus using technology described in WO2013/076280. To amplify the 5′ and 3′ integration flanks for the integration locus, suitable primers and genomic DNA from a CEN.PK yeast strain (van Dijken et al. Enzyme and Microbial Technology 26 (2000) 706-714) was used. The different genes were ordered as cassettes (containing homologous sequence, promoter, gene, terminator, homologous sequence) at DNA2.0. The genes in these cassettes were flanked by constitutive promoters and terminators. See Table 1. Plasmid DNA from DNA2.0 containing the ERG20, tHMG1 and BTS1 cassettes were dissolved to a concentration of 100 ng/μl. In a 50 μl PCR mix 20 ng template was used together with 20 pmol of the primers. The material was dissolved to a concentration of 0.5 μg/μl.

TABLE 1 Composition of the over-expression constructs Promoter ORF Terminator Eno2 (SEQ ID Erg20 (SEQ ID Adh1 (SEQ ID NO: 201) NO: 81) NO: 212) Fba1 (SEQ ID tHMG1 (SEQ ID Adh2 (SEQ ID NO: 202) NO: 79) NO: 213) Tef1 (SEQ ID Bts1 (SEQ ID Gmp1 (SEQ ID NO: 203) NO: 83) NO: 214)

For amplification of the selection marker, the pUG7-EcoRV construct (FIG. 1) and suitable primers were used. The KanMX fragment was purified from gel using the Zymoclean Gel DNA Recovery kit (ZymoResearch). Yeast strain Cen.PK113-3C was transformed with the fragments listed in Table 2.

TABLE 2 DNA fragments used for transformation of ERG20, tHMG1 and BTS1 Fragment 5′YPRcTau3 ERG20 cassette tHMG1 cassette KanMX cassatte BTS1 cassette 3′YPRcTau3

After transformation and recovery for 2.5 hours in YEPhD (yeast extract phytone peptone glucose; BBL Phytone Peptone from BD) at 30° C. the cells were plated on YEPhD agar with 200 μg/ml G418 (Sigma). The plates were incubated at 30° C. for 4 days. Correct integration was established with diagnostic PCR and sequencing. Over-expression was confirmed with LC/MS on the proteins. The schematic of the assembly of ERG20, tHMG1 and BTS1 is illustrated in FIG. 2. This strain was named STV002.

Expression of the CRE-recombinase in this strain led to out-recombination of the KanMX marker. Correct out-recombination, and presence of ERG20, tHMG and BTS1 was established with diagnostic PCR.

1.2 Knock-Down of Erg9

For reducing the expression of Erg9, an Erg9 knock down construct was designed and used that contains a modified 3′ end, that continues into the TRP1 promoter driving TRP1 expression.

The construct containing the Erg9-KD fragment was transformed to E. coli TOP10 cells. Transformants were grown in 2PY(2 times Phytone peptone Yeast extract), sAMP medium. Plasmid DNA was isolated with the QIAprep Spin Miniprep kit (Qiagen) and digested with SalI-HF (New England Biolabs). To concentrate, the DNA was precipitated with ethanol. The fragment was transformed to S. cerevisiae, and colonies were plated on mineral medium (Verduyn et al, 1992. Yeast 8:501-517) agar plates without tryptophan. Correct integration of the Erg9-KD construct was confirmed with diagnostic PCR and sequencing. The schematic of performed transformation of the Erg9-KD construct is illustrated in FIG. 3. The strain was named STV003.

1.3 Over-Expression of UGT2_1a

For over-expression of UGT2_1a, technology was used as described in co-pending patent application nos. WO2013/076280 and WO2013/144257. The UGT2a was ordered as a cassette (containing homologous sequence, promoter, gene, terminator, homologous sequence) at DNA2.0. For details, see Table 3. To obtain the fragments containing the marker and Cre-recombinase, technology was used as described in co-pending patent application no. WO2013/135728. The NAT marker, conferring resistance to nourseothricin was used for selection.

TABLE 3 Composition of the over-expression construct Promoter ORF Terminator Pgk1 (SEQ ID UGT2_1a (SEQ ID Adh2 (SEQ ID NO: 204) NO: 87) NO: 213)

Suitable primers were used for amplification. To amplify the 5′ and 3′ integration flanks for the integration locus, suitable primers and genomic DNA from a CEN.PK yeast strain was used.

S. cerevisiae yeast strain STV003 was transformed with the fragments listed in Table 4, and the transformation mix was plated on YEPhD agar plates containing 50 μg/ml nourseothricin (Lexy NTC from Jena Bioscience).

TABLE 4 DNA fragments used for transformation of UGT2a Fragment 5′Chr09.01 UGT2a cassette NAT-CR RE 3′Chr09.01

Expression of the CRE recombinase is activated by the presence of galactose. To induce the expression of the CRE recombinase, transformants were restreaked on YEPh Galactose medium. This resulted in out-recombination of the marker(s) located between lox sites. Correct integration of the UGT2a and out-recombination of the NAT marker was confirmed with diagnostic PCR. The resulting strain was named STV004. The schematic of the performed transformation of the UGT2a construct is illustrated in FIG. 4.

1.4 Over-Expression of Production Pathway to RebA: CPS, KS, KO, KAH, CPR, UGT1, UGT3 and UGT4

All pathway genes leading to the production of RebA were designed to be integrated in one locus in the STV004 strain background. To amplify the 5′ and 3′ integration flanks for the integration locus (site 3), suitable primers and genomic DNA from a CEN.PK yeast strain was used. The different genes were ordered as cassettes (containing homologous sequence, promoter, gene, terminator, homologous sequence) at DNA2.0 (see Table 5 for overview). The DNA from DNA2.0 was dissolved to 100 ng/μl. This stock solution was further diluted to 5 ng/μl, of which 1 μl was used in a 50 μl-PCR mixture. The reaction contained 25 pmol of each primer. After amplification, DNA was purified with the NucleoSpin 96 PCR Clean-up kit (Macherey-Nagel) or alternatively concentrated using ethanol precipitation.

TABLE 5 Composition of the over-expression constructs for CPS, KS, KO, KAH, CPR, UGT1, UGT3 and UGT4 Promoter ORF Terminator Kl prom 12.pro (SEQ ID NO: 205) CPS (SEQ ID NO: 61) Sc Adh2.ter (SEQ ID NO: 213) Sc Pgk1.pro (SEQ ID NO: 204) KS (SEQ ID NO: 65) Sc Tal1.ter (SEQ ID NO: 215) Sc Eno2.pro (SEQ ID NO: 201) KO (SEQ ID NO: 23) Sc Tpi1.ter (SEQ ID NO: 216) Ag lox_Tef1.pro (SEQ ID NO: 206) KANMX (SEQ ID NO: 211) Ag Tef1_lox.ter (SEQ ID NO: 217) Sc Tef1.pro (SEQ ID NO: 203) KAH (SEQ ID NO: 33) Sc Gpm1.ter (SEQ ID NO: 214) Kl prom 6.pro (SEQ ID NO: 207) CPR (SEQ ID NO: 77) Sc Pdc1.ter (SEQ ID NO: 218) Sc Pma1.pro (SEQ ID NO: 208) UGT1 (SEQ ID NO: 71) Sc Tdh1.ter (SEQ ID NO: 219) Sc Vps68.pro (SEQ ID NO: 209) UGT3 (SEQ ID NO: 73) Sc Adh1.ter (SEQ ID NO: 212) Sc Oye2.pro (SEQ ID NO: 210) UGT4 (SEQ ID NO: 75) Sc Eno1.ter (SEQ ID NO: 220)

All fragments for the pathway to RebA, the marker and the flanks (see overview in Table 6) were transformed to a S. cerevisiae yeast strain STV004. After overnight recovery in YEPhD at 20° C. the transformation mixes were plated on YEPhD agar containing 200 μg/ml G418. These were incubated 3 days at 30° C.

TABLE 6 DNA fragments used for transformation of CPS, KS, KO, KanMX, KAH, CPR, UGT1, UGT3 and UGT4 Fragment 5′ INT1 CPS cassette KS cassette KO cassette KanMX cassette KAH cassette CPR cassette UGT1 cassette UGT3 cassette UGT4 cassette 3′INT1

Correct integration was confirmed with diagnostic PCR and sequence analysis (3500 Genetic Analyzer, Applied Biosystems). The sequence reactions were done with the BigDye Terminator v3.1 Cycle Sequencing kit (Life Technologies). Each reaction (10 μI) contained 50 ng template and 3.2 pmol primer. The products were purified by ethanol/EDTA precipitation, dissolved in 10 μI HiDi formamide and applied onto the apparatus. The strain was named STV016. The schematic of how the pathway from GGPP to RebA is integrated into the genome is illustrated in FIG. 5. Table 7 sets out the strains used in this Example 1.

TABLE 7 Table of strains Strain Background Genotype Cen.PK113-3C — MATa URA3 HIS3 LEU2 trp1-289 MAL2-8C SUC2 STV002 Cen.PK113-3C MATa URA3 HIS3 LEU2 trp1-289 MAL2-8C SUC2 YPRcTau3::ERG20, tHMG1, KanMX, BTS1 STV003 STV002 MATa URA3 HIS3 LEU2 trp1-289 MAL2-8C SUC2 YPRcTau3::ERG20, tHMG1, KanMX, BTS1 ERG9::ERG9-KD TRP1 STV004 STV003 MATa URA3 HIS3 LEU2 trp1-289 MAL2-8C SUC2 YPRcTau3::ERG20, tHMG1, BTS1 ERG9::ERG9-KD TRP1 Chr09.01::UGT91D2 STV016 STV004 MATa URA3 HIS3 LEU2 trp1-289 MAL2-8C SUC2 YPRcTau3::ERG20, tHMG1, BTS1 ERG9::ERG9-KD TRP1 Chr09.01::UGT2_1a INT1::CPS, KS, KO, KanMX, KAH, CPR, UGT1, UGT3, UGT4 1.5 Fermentation of STV016

The S. cerevisiae strain STV016 constructed as described above, were cultivated in shake-flasks (2 l with 200 ml medium) for 32 hours at 30° C. and 220 rpm. The medium was based on Verduyn et al. (Verduyn C, Postma E, Scheffers W A, Van Dijken J P. Yeast, 1992 July; 8(7):501-517), with modifications in the carbon and nitrogen sources, as described in Table 8.

TABLE 8 Preculture medium composition Concentration Raw material Formula (g/kg) Galactose C₆H₁₂O₆ 20.0 Urea (NH₂)₂CO 2.3 Potassium dihydrogen phosphate KH₂PO₄ 3.0 Magnesium sulphate MgSO₄•7H₂O 0.5 Trace element solution 1 Vitamin solution 1 Concentration Component Formula (g/kg) ^(a)Trace elements solution EDTA C₁₀H₁₄N₂Na₂O₈•2H₂O 15.00 Zincsulphate•7H₂O ZnSO₄•7H₂O 4.50 Manganesechloride•2H₂O MnCl₂•2H₂O 0.84 Cobalt (II) chloride•6H₂O CoCl₂•6H₂O 0.30 Cupper (II) sulphate•5H₂O CuSO₄•5H₂O 0.30 Sodium molybdenum•2H₂O Na₂MoO₄•2H₂O 0.40 Calciumchloride•2H₂O CaCl₂•2H₂O 4.50 Ironsulphate•7H₂O FeSO₄•7H₂O 3.00 Boric acid H₃BO₃ 1.00 Potassium iodide Kl 0.10 ^(b)Vitamin solution Biotin (D−) C₁₀H₁₆N₂O₃S 0.05 Ca D(+) panthothenate C₁₈H₃₂CaN₂O₁₀ 1.00 Nicotinic acid C₆H₅NO₂ 1.00 Myo-inositol C₆H₁₂O₆ 25.00 Thiamine chloride C₁₂H₁₈Cl₂N₄OS•xH₂O 1.00 hydrochloride Pyridoxol hydrochloride C₈H₁₂ClNO₃ 1.00 p-aminobenzoic acid C₇H₇NO₂ 0.20

Subsequently, 200 ml of the content of the shake-flask was transferred into a fermenter (starting volume 5 L), which contained the medium as set out in Table 9.

TABLE 9 Composition fermentation medium Final Concentration Raw material (g/kg) Glucose•1aq C₆H₁₂O₆•1H₂O 4.4 Ammonium sulphate (NH₄)₂SO₄ 1 Potassium dihydrogen phosphate KH₂PO₄ 10 Magnesium sulphate MgSO₄•7H₂O 5 Trace element solution — 8 Vitamin solution — 8

The pH was controlled at 5.0 by addition of ammonia (25 wt %). Temperature was controlled at 27° C. pO₂ was controlled at 40% by adjusting the stirrer speed. Glucose concentration was kept limited by controlled feed to the fermenter as set out in Table 10.

TABLE 10 Composition of the fermentation feed medium Final Concentration Raw material Formula (g/kg) Glucose•1aq C₆H₁₂O₆•1H₂O 550 Potassium dihydrogen KH₂PO₄ 15.1 phosphate Magnesium sulphate MgSO₄•7H₂O 7.5 heptahydrate Verduyn trace elements 12 solution Verduyn vitamin solution 12

Example 2 Observation of 7.1, 7.2 and 7.3 Using LC-MS

Steviol glycosides containing 7 glucose molecules (further referred to as 7.1, 7.2 and 7.3) were observed with the LC-MS system described below in the mother liquid after crystallization of rebaudioside A in a water/ethanol mixture (strain STV016). Prior to purification the sample was concentrated by evaporation.

7.1, 7.2 and 7.3 were analyzed on an Acquity UPLC (Waters) coupled to a XEVO-TQ Mass Spectrometer (Waters) equipped with an electrospray ionization source operated in the negative-ion mode in MRM mode at the deprotonated molecules for all steviol glycosides studied, among these m/z 1451.5, representing the deprotonated molecule of a steviol glycoside containing 7 glucose molecules.

The chromatographic separation was achieved with a 2.1×100 mm 1.8 μm particle size, Acquity UPLC® HSS T3 column, using a gradient elution with (A) 50 mM ammonium acetate in LC-MS grade water, and B) LC-MS grade acetonitrile as mobile phases. The 4 min gradient started from 30% B linearly increasing to 35% B in 0.5 minutes and kept at 35% B for 0.8 minutes, then linearly increased to 95% B in 0.7 minutes and kept there for 0.5 minutes, then re-equilibrating with 30% B for 1.5 min. The flow rate was kept at 0.6 ml/min, using an injection volume of 5 μI and the column temperature was set to 50° C. The individual compounds, 7.1, 7.2 and 7.3, observed for m/z 1451.5 elute at retention times 0.59, 0.71 and 0.74 minutes.

For the analysis of elemental composition of 7.1, 7.2 and 7.3 HRMS (High Resolution Mass Spectrometry) analysis was performed with an LTQ-Orbitrap Fourier Transform Mass Spectrometer (Thermo Electron) equipped with an electrospray ionization source operated in the negative-ion mode, scanning from m/z 300-2000.

The chromatographic separation was achieved with an Acella LC system (Thermo Fisher) with the same column and gradient system as described above.

Using this chromatographic system the individual compounds elute at retention times 0.84, 1.20 and 1.30 minutes, respectively as shown in FIG. 6a , and 7.1, 7.2 and 7.3 were characterized at respectively m/z 1451.5786, 1451.5793, and 1451.5793, which is in good agreement with the theoretical m/z value of 1451.5820 (respectively−1.8 and −2.3 ppm). The corresponding chemical formula of these components is C₆₂H₁₀₀O₃₈ for the uncharged species.

Example 3 Purification of 7.1, 7.2. and 7.3 Using Preparative LC-UV

Purification of 7.1, 7.2 and 7.3 was performed from the ethanol extract of Saccharomyces broth (strain STV016) containing minimal amount of the compounds of interest. Preparative separation was performed using Reversed Phase chromatography (Waters Atlantis T3, 30*150 mm, 5 um), gradient elution with LC-MS grade water and acetonitrile as eluent. A flow-rate of 40 ml/min and an injection volume of 300 ul was used.

Approximately 100 injections were performed and the compounds of interest were triggered by UV detection at 210 nm. All fractions of 7.1, 7.2 and 7.3 were pooled and freeze dried, before LC-MS and NMR analysis.

LC-MS of 7.1, 7.2 and 7.3 for Mass Confirmation and Purity Determination After Preparative Purification, Using LC-MS.

The purity of 7.1, 7.2 and 7.3 was analyzed on an Acquity UPLC (Waters) coupled to a XEVO-TQ Mass Spectrometer (Waters) equipped with an electrospray ionization source operated in the negative-ion mode in MRM mode at the deprotonated molecules for all steviol glycosides studied, among these m/z 1451.5, representing the deprotonated molecule of a steviol glycoside containing 7 glucose molecules. 7.1 eluting at retention time 0.59 minutes could be estimated to be over 80% pure, whereas 7.2 and 7.3, eluting at retention times 0.71 and 0.74 minutes, could be estimated to be over 90% pure and 7.3 still contains about 5% of 7.2, shown in FIG. 6 b.

Using HRMS (High Resolution Mass Spectrometry) analysis was performed with an LTQ-Orbitrap Fourier Transform Mass Spectrometer (Thermo Electron) equipped with an electrospray ionization source operated in the negative-ion mode the elemental composition of the individual compound was checked and found to be in agreement with the theoretical mass corresponding to the chemical formula of C₆₂H₁₀₀O₃₈ for the uncharged species.

Example 4 Analysis of Rebaudioside 7.1

1.1 mg of fraction 7.1 obtained as described in Example 3 was dissolved in 1.3 mL of CDCl₃/pyridine-d5 1/3 (w/w) and 2 drops of DCOOD.

A series of COSY and TOCSY 2D NMR spectra with small increments of the mixing time afforded the assignment of almost all protons of each spin system (of the seven sugar units) for all three Rebaudiosides as well as the ent-kaurane diterpenoid core. The HSQC experiment allowed for the assigment of corresponding C—H couples.

The anomeric H of glc^(I) and glc^(II) were identified based on their long range correlation in HMBC to the protons of the ent-kaurane diterpenoid core.

The long range correlation of H2^(I)-H1^(V) and H3^(I)-H1^(VI) and H2^(II)-H1^(III) and H3^(II)-H^(IIII) observed in corresponding ROESY spectra allowed the assigment of the substitution sites of glc^(I) and glc^(II). The assigment was also corroborated by the long range correlation in HMBC experiment of the anomeric protons of glc^(III) up to glc^(VI) with the ¹³C atoms of glc^(l) and glc^(II), namely H1^(III)-C2^(II), H1^(IIII)-C3^(II), H1^(V)-C2^(I) and H1^(IV)-C3^(I). The position of sugars glc^(III), glc^(IV), glc^(V) and glc^(VI) is identical as in the structure of Rebaudioside M (FIG. 10).

The down field shift of the anomeric H1^(VII) (5.86 ppm vs. 4.5-4.6 ppm) and small coupling constant (3.8 Hz vs. 7.8 Hz) indicates that the seventh sugar residue has the a configuration.

The position of the 7^(th) sugar in Rebaudioside 7.1 could be identified from the long range HMBC coupling of H1^(VII) and C3^(III) long range proton coupling of H1^(VII)-H3^(III) ROESY experiment and the low field shift of the C3^(III) (83.8 ppm as compared to unsubstituted C3 atoms around 78-79 ppm). The structure of rebaudioside 7.1 is depicted in FIG. 7. All ¹H and ¹³C NMR chemical shifts for Rebaudioside 7.1 are listed in Table 11. For the sake of comparison also the data of Rebaudioside M are included.

TABLE 11 ¹H and ¹³C NMR chemical shifts of Rebaudioside 7.1 in CDCl₃/pyridine 1/3 and 3 drops of DCOOD recorded at 320K and Rebaudioside M in CDCl₃/pyridine 1/1 and 3 drops of DCOOD recorded at 300K, δ_(TMS) = 0 Rebaudioside M Rebaudioside 7.1 Position ¹H ¹³C ¹H ¹³C  1 0.77 (dt, 13.5& 4 Hz)&1.76 (m) 39 0.74 (dt, 13.6& 4.2 Hz)&1.72 (m) 41.6  2 1.35&2.12 (m) 19.1 1.69 & 2.06 (m) 17.4  3 1.0 (dt, 13.2&4.7)&2.14 (m) 38.2 0.99 (m) &2.33 (d, 13 Hz) 38.2  4 — 43.8 — 43.8  5 1.02 (t, 13 Hz) 57 1.01 (d, 14.1 Hz) 58.6  6 2.03 (m)&2.17 (m) 23.2 1.93 & 2.11 (m) 23.9  7 1.37&1.66 (m) 42.2 1.38 & 1.53 (m) 43.5  8 — 40.6 — 42.5  9 0.89 (d, 8.1 Hz) 54.1 0.88 (d, 7.7 Hz) 55.3 10 — 40 — 40.9 11 1.57 & 1.68(m) 19.8 1.56 & 1.64 (m) 21.3 12 1.66&2.43 (m) 37.9 1.66 & 2.28 (m) 39.5 13 — 87.3 — 88.6 14 1.76 (m) &2.49(d, 10.9 Hz) 42.7 1.72 & 2.40 (m) 44.8 15 1.83&1.99 (d, 17.3 Hz) 45.9 1.89 & 1.99 (d, 17 Hz) 48.1 16 — 152.2 — 154 17 4.78&5.42 (s) 104.6 4.85 & 5.45 (s) 105.9 18 1.21 (s) 27 1.22 (s) 29.8 19 — 176.4 — 176.1 20 1.15 (s) 16.1 1.08 (s) 15.9  1^(I) 5.98 (d, 8.3 Hz) 94.6 5.99 (d, 8.2 Hz) 94.9  2^(I) 4.22 (t, 8.6 Hz) 76.1 4.28 (m) 77.5  3^(I) 4.88 (t, 8.7 Hz) 87.9 4.52 (t, 9.2 Hz) 89.9  4^(I) 3.88 (m) 69.6 4.00 (m) 71.1  5^(I) 3.86 (m) 77.5 4.11 (m) 78.8  6^(I) 4.06 &3.92 (m) 61.4 5.06 & 3.98 (m) 62.7  1^(II) 5.15 (d, 7.7 Hz) 95.3 5.07 (d, 7.8 Hz) 97.3  2^(II) 3.81 (m) 80.8 3.87 (m) 82.4  3^(II) 4.67 (t, 9 Hz) 87 4.58 (t, 9.1 Hz) 88  4^(II) 3.68 (m) 69.9 3.76 (m) 71  5^(II) 3.74 (m) 77.1 3.63 (m) 78.4  6^(II) 4.06&3.92 (m) 62.3 4.09 & 3.95 (m) 63.6  1^(III) 5.13 (d, 7.6 Hz) 104 5.22 (d, 8.2 Hz) 105.24  2^(III) 3.81 (m) 74.9 3.72 (m) 75.1  3^(III) 3.81 (m) 77.8 4.04 (m) 83.8  4^(III) 3.60 (m) 72.8 3.87 (m) 74.1  5^(III) 3.45 (m) 76.3 3.42 (m) 77.9  6^(III) 4.2&3.91 (m) 63.6 4.12 & 3.92 (m) 64.4  1^(IV) 5.147 (d, 8.1 Hz) 103.1 5.34 (d, 7.8 Hz) 104.6  2^(IV) 3.69 (m) 74.6 3.75 (m) 76.2  3^(IV) 4.20 (m) 76.9 4.21 (m) 78.9  4^(IV) 3.74 (m) 69.9 3.87 (m) 72.5  5^(IV) 3.81 (m) 77.2 3.88 (m) 78.9  6^(IV) 4.07&3.85 (m) 61.5 4.18 & 3.95 (m) 63.2  1^(V) 5.47 (d, 7.8 Hz) 103.5 5.42 (d, 7.8 Hz) 104.9  2^(V) 3.88 (m) 74.7 3.83 (m) 75.8  3^(V) 3.76 (m) 77.1 3.95 (m) 78.9  4^(V) 3.79 (m) 73.2 3.79 (m) 74.5  5^(V) 3.57 (m) 76.2 3.69 (m) 78.5  6^(V) 4.28 (dd, 11.1 & 4.1 Hz)&4.01 (m) 63.6 4.32 & 4.08 (m) 64.8  1^(VI) 5.05 (d, 7.8 Hz) 103.4 5.3 (d, 7.8 Hz) 105.6  2^(VI) 3.68 (m) 76.9 3.76 (m) 76.2  3^(VI) 4.06 (m) 77.1 3.98 (m) 78.9  4^(VI) 3.77 (m) 70.5 3.77 (m) 72.4  5^(VI) 3.59 m) 77.2 4.07 (m) 78.8  6^(VI) 4.08&3.83 (m) 61.6 4.28 & 3.92 (m) 63.5  1^(VII) — 5.86 (d, 3.6 Hz) 100.7  2^(VII) — 3.87 (m) 74.2  3^(VII) — 4.93 (t, 9.5 Hz) 75.7  4^(VII) — 3.68 (m) 74.3  5^(VII) — 4.65 (m) 74.2  6^(VII) — 4.31 & 4.02 (m) 64.8

Example 5 Analysis of Rebaudioside 7.2

2.5 mg of sample was dissolved in 1 mL of CDCl₃/pyridine-d5 1/1 (w/w) and 2 drops of DCOOD.

A series of COSY and TOCSY 2D NMR spectra with small increments of the mixing time afforded the assignment of almost all protons of each spin system (of the seven sugar units) for all three Rebaudiosides as well as the ent-kaurane diterpenoid core. The HSQC experiment allowed for the assigment of corresponding C—H couples.

The anomeric H of glc^(I) and glc^(II) were identified based on their long range correlation in HMBC to the protons of the ent-kaurane diterpenoid core.

The position of sugars glc^(III), glc^(IV), glc^(V) and glc^(VI) is identical as in the structure of Rebaudioside M and the assignment is described in more detail in section dedicated to assignment of structure of Rebaudioside 7.1.

The position of the 7^(th) sugar in Rebaudioside 7.2 could be identified from the long range HMBC coupling of H6^(IV) and C1^(VII), long range proton coupling of H1^(VII)-H6^(IV) in ROESY experiment and the low field shift of the C6^(IV) (69.4 ppm as compared to remaining C6 atoms 62-64 ppm). The 7^(th) sugar is attached via β-glycosidic bond to Glc^(IV). The structure of rebaudioside 7.2 is depicted in FIG. 8. All ¹H and ¹³C NMR chemical shifts of Rebaudioside 7.2 are listed in Table 12. For the sake of comparison also the data of Rebaudioside M are included.

TABLE 12 ¹H and ¹³C NMR chemical shifts of Rebaudioside 7.2 in CDCl₃/pyridine 1/1 and 2 drops of DCOOD and Rebaudioside M in CDCl₃/pyridine 1/1 and 3 drops of DCOOD recorded at 300K, δ_(TMS) = 0 Rebaudioside M Rebaudioside 7.2 Position ¹H ¹³C ¹H ¹³C  1 0.77 (dt, 13.5& 4 Hz)&1.76 (m) 39 0.77 (dt, 13.3& 4 Hz)&1.76 (m) 39.9  2 1.35&2.12 (m) 19.1 1.35 & (2.13 (m) 18.6  3 1.0 (dt, 13.2&4.7)&2.14 (m) 38.2 0.99 (dt, 14&4.6) &2.12 (m) 38.3  4 — 43.8 — 43.1  5 1.02 (t, 13 Hz) 57 1.02 (13.1 Hz) 57.1  6 2.03 (m)&2.17 (m) 23.2 2.02 & 2.15 (m) 22.7  7 1.37&1.66 (m) 42.2 1.37 (m)&1.66 (m) 42.3  8 — 40.6 — 40  9 0.89 (d, 8.1 Hz) 54.1 0.89 (d, 7.6 Hz) 54.1 10 — 40 — 39.1 11 1.57 &1.68(m) 19.8 1.57 & 1.69 (m) 19.3 12 1.66&2.43 (m) 37.9 1.64 & 2.42 (m) 37.9 13 — 87.3 — 86.8 14 1.76 (m) &2.49(d, 10.9 Hz) 42.7 1.75 (m)&2.46 (d, 10.9 Hz) 42.8 15 1.83&1.99 (d, 17.3 Hz) 45.9 1.84 &1.99 (d, 17 Hz) 45.9 16 — 152.2 — 151.6 17 4.78&5.42 (s) 104.6 4.77&5.39 (s) 104.5 18 1.21 (s) 27 1.22 (s) 27.5 19 — 176.4 — 176.1 20 1.15 (s) 16.1 1.14 (s) 15.7  1^(I) 5.98 (d, 8.3 Hz) 94.6 5.97 (d, 8.4 Hz) 94.7  2^(I) 4.22 (t, 8.6 Hz) 76.1 4.21 (t, 8.8 Hz) 76.4  3^(I) 4.88 (t, 8.7 Hz) 87.9 4.92 (t, 8 Hz) 87.1  4^(I) 3.88 (m) 69.6 3.84 (m) 70.7  5^(I) 3.86 (m) 77.5 3.84 (m) 76.9  6^(I) 4.06 &3.92 (m) 61.4 4.04&3.91 (m) 61.5  1^(II) 5.15 (d, 7.7 Hz) 95.3 5.13 (d, 7.4 Hz) 95.2  2^(II) 3.81 (m) 80.8 3.78 (m) 80.5  3^(II) 4.67 (t, 9 Hz) 87 4.62 (t, 9.1 Hz) 88  4^(II) 3.68 (m) 69.9 3.63(m) 70.5  5^(II) 3.74 (m) 77.1 3.65 (m) 76.6  6^(II) 4.06&3.92 (m) 62.3 4.1&3.99 (m) 61.9  1^(III) 5.13 (d, 7.6 Hz) 104 5.04 (d, 8.1 Hz) 104.3  2^(III) 3.81 (m) 74.9 3.81 (m) 74.7  3^(III) 3.81(m) 77.8 3.76 (m) 77.6  4^(III) 3.60 (m) 72.8 3.57 (m) 73  5^(III) 3.45 (m) 76.3 3.42 (m) 76.2  6^(III) 4.2&3.91 (m) 63.6 4.17&3.91 (m) 63.8  1^(IV) 5.147 (d, 8.1 Hz) 103.1 4.94 (d, 8 Hz) 103.5  2^(IV) 3.69 (m) 74.6 3.65 (m) 74.4  3^(IV) 4.20 (m) 76.9 4.06 (m) 76.6  4^(IV) 3.74 (m) 69.9 3.83 (m) 69.7  5^(IV) 3.81 (m) 77.2 3.58 (m) 77.3  6^(IV) 4.07&3.85 (m) 61.5 4.43 (d, 9.6 Hz)&3.63 (m) 69.4  1^(V) 5.47 (d, 7.8 Hz) 103.5 5.51 (d, 7.4 Hz) 103.4  2^(V) 3.88 (m) 74.7 3.88 (m) 74.8  3^(V) 3.76 (m) 77.1 3.89(m) 77.6  4^(V) 3.79 (m) 73.2 3.77 (m) 73.3  5^(V) 3.57 (m) 76.2 3.55 (m) 76.1  6^(V) 4.28 (dd, 11.1 & 4.1 Hz)&4.01 (m) 63.6 4.25 (dd, 11.1&3.8 Hz)&3.98 (m) 63.7  1^(VI) 5.05 (d, 7.8 Hz) 103.4 5.18 (d, 8.1 Hz) 103.14  2^(VI) 3.68 (m) 76.9 3.69 (m) 74.7  3^(VI) 4.06 (m) 77.1 4.12 (t, 9.1 Hz) 77.2  4^(VI) 3.77 (m) 70.5 3.82 (m) 70.6  5^(VI) 3.59 m) 77.2 3.71 (m) 77.2  6^(VI) 4.08&3.83 (m) 61.6 4.03&3.82(m) 61.4  1^(VII) — 4.47 (d, 7.8 Hz) 103.6  2^(VII) — 3.62 (m) 74.5  3^(VII) — 3.84 (m) 77.7  4^(VII) — 3.57 (m) 75.6  5^(VII) — 3.82 (m) 77.3  6^(VII) — 4.2&4.06 (m) 62

Example 6 Analysis of Rebaudioside 7.3

2.3 mg of sample was dissolved in 1 mL of CDCl₃/pyridine-d5 1/2 (w/w) and 3 drops of DCOOD.

A series of COSY and TOCSY 2D NMR spectra with small increments of the mixing time afforded the assignment of almost all protons of each spin system (of the seven sugar units) for all three Rebaudiosides as well as the ent-kaurane diterpenoid core. The HSQC experiment allowed for the assigment of corresponding C—H couples.

The anomeric H of glc^(I) and glc^(II) were identified based on their long range correlation in HMBC to the protons of the ent-kaurane diterpenoid core.

The position of sugars glc^(III), glc^(IV), glc^(V) and glc^(VI) is identical as in the structure of Rebaudioside M and the assignment is described in more detail in section dedicated to assignment of structure of Rebaudioside 7.1.

The position of the 7^(th) sugar in Rebaudioside 7.3 could be identified from the long range HMBC coupling of H1^(VII) and C6^(VI), long range proton coupling of H1^(VII)-H6^(VI) in ROESY experiment and the low field shift of the C6^(VI) (69.5 ppm as compared to remaining C6 atoms 61-63 ppm). The 7^(th) sugar is attached via β-glycosidic bond to Glc^(VI). The structure of rebaudioside 7.3 is depicted in FIG. 9. All ¹H and ¹³C NMR chemical shifts of Rebaudioside 7.3 are listed in Table 13. For the sake of comparison also the data of Rebaudioside M are included.

TABLE 13 ¹H and ¹³C NMR chemical shifts of Rebaudioside 7.3 in CDCl₃/pyridine 1/2 and 3 drops of DCOOD and Rebaudioside M in CDCl₃/pyridine 1/1 and 3 drops of DCOOD recorded at 300K, δ_(TMS) = 0 Rebaudioside M Rebaudioside 7.3 Position ¹H ¹³C ¹H NMR ¹³C  1 0.77 (dt, 13.5& 4 Hz)&1.76 (m) 39 0.79 (dt, 14&4.3 Hz)&1.77 (m) 39.9  2 1.35&2.12 (m) 19.1 1.38&2.18 (m) 19.1  3 1.0 (dt, 13.2&4.7)&2.14 (m) 38.2 1.03 (m)&2.17 (m) 38.1  4 — 43.8 — 43.7  5 1.02 (t, 13 Hz) 57 1.04 (t, 12.8 Hz) 57  6 2.03 (m)&2.17 (m) 23.2 2.09&2.21 (m) 23.3  7 1.37&1.66 (m) 42.2 1.41&1.69 (m) 42.1  8 — 40.6 — 40.5  9 0.89 (d, 8.1 Hz) 54.1 0.91 (d, 8 Hz) 53.9 10 — 40 — 39.4 11 1.57 &1.68(m) 19.8 1.59&1.72 (m) 19.9 12 1.66&2.43 (m) 37.9 1.68&2.48 (m) 38 13 — 87.3 — 87.4 14 1.76 (m) &2.49(d, 10.9 Hz) 42.7 1.81 (d, 10.4 Hz)&2.53 (d, 10.4 Hz) 42.1 15 1.83&1.99 (d, 17.3 Hz) 45.9 1.87 (d, 17.9 Hz)&2.01 (d, 17.9 Hz) 46 16 — 152.2 — 152.3 17 4.78&5.42 (s) 104.6 4.84&5.47 (s) 104.6 18 1.21 (s) 27 1.27 (s) 27.9 19 — 176.4 — 176.3 20 1.15 (s) 16.1 1.2 (s) 16.4  1^(I) 5.98 (d, 8.3 Hz) 94.6 6.06 (d, 8.6 Hz) 94.5  2^(I) 4.22 (t, 8.6 Hz) 76.1 4.29 (t, 8.7 Hz) 76.1  3^(I) 4.88 (t, 8.7 Hz) 87.9 4.87 (t, 8.7 Hz) 88.6  4^(I) 3.88 (m) 69.6 3.99 (m) 69.3  5^(I) 3.86 (m) 77.5 3.89 (m) 77.3  6^(I) 4.06 &3.92 (m) 61.4 4.04&4.10 (m) 61  1^(II) 5.15 (d, 7.7 Hz) 95.3 5.19 (d, 7.1 Hz) 95.4  2^(II) 3.81 (m) 80.8 3.87 (m) 80.8  3^(II) 4.67 (t, 9 Hz) 87 4.72 (t, 9.5 Hz) 86.9  4^(II) 3.68 (m) 69.9 3.81 (m) 69.6  5^(II) 3.74 (m) 77.1 3.70 (m) 77  6^(II) 4.06&3.92 (m) 62.3 4.10&3.99 (m) 61.9  1^(III) 5.13 (d, 7.6 Hz) 104 5.22 (d, 7.4 Hz) 104.1  2^(III) 3.81 (m) 74.9 3.90 (m) 74.9  3^(III) 3.81(m) 77.8 3.92 (m) 77.6  4^(III) 3.60 (m) 72.8 3.65 (m) 72.7  5^(III) 3.45 (m) 76.3 3.55 (m) 76.8  6^(III) 4.2&3.91 (m) 63.6 4.27 &3.99 (m) 63.4  1^(IV) 5.147 (d, 8.1 Hz) 103.1 5.32 (d, 8.0 Hz) 103.2  2^(IV) 3.69 (m) 74.6 3.77 (m) 74.8  3^(IV) 4.20 (m) 76.9 4.23 (m) 77.3  4^(IV) 3.74 (m) 69.9 3.89 (m) 70.7  5^(IV) 3.81 (m) 77.2 3.90 (m) 77.5  6^(IV) 4.07&3.85 (m) 61.5 4.15 (d, 11.3 Hz)&3.91 (m) 61.5  1^(V) 5.47 (d, 7.8 Hz) 103.5 5.53 (d, 7.8 Hz) 103.5  2^(V) 3.88 (m) 74.7 3.91 (m) 74.9  3^(V) 3.76 (m) 77.1 3.93 (m) 77.6  4^(V) 3.79 (m) 73.2 3.84 (m) 73  5^(V) 3.57 (m) 76.2 3.66 (m) 77.3  6^(V) 4.28 (dd, 11.1 & 4.1 Hz)&4.01 (m) 63.6 4.37 (dd, 12&4.3 Hz)&4.08 (m) 63.4  1^(VI) 5.05 (d, 7.8 Hz) 103.4 5.08 (d, 8.0 Hz) 103.6  2^(VI) 3.68 (m) 76.9 3.74 (m) 74.4  3^(VI) 4.06 (m) 77.1 4.09 (m) 77.1  4^(VI) 3.77 (m) 70.5 3.70 (m) 70.6  5^(VI) 3.59 m) 77.2 3.71 (m) 75.9  6^(VI) 4.08&3.83 (m) 61.6 4.52 (d, 8.7 Hz)&3.70 (m) 69.5  1^(VII) — 4.59 (d, 7.8 Hz) 103.6  2^(VII) — 3.68 (m) 74.6  3^(VII) — 3.93 (m) 77  4^(VII) — 3.91 (m) 70.7  5^(VII) — 3.67 (m) 76.7  6^(VII) — 4.21 (m)&4.1 (m) 61.8

In summary, three new rebaudiosides were determined as set out in Table 14.

TABLE 14 Summary of new Rebaudiosides Steviol glycosides compound R₁ R₂ 7.1

7.2

7.3

General Materials and Methods (NMR Analysis)

The solvent mixture was optimized for each of the Rebaudioside samples to obtain the best possible resolution of the signals of the anomeric protons. The amount of samples and the amount of solvent is critical for the resolution of the peaks as the shift of the peaks, especially the anomeric ones, are concentration and pH dependent (FIG. 12).

The spectra of Rebaudiosides 7.2 and 7.3 were recorded at 300K while in case of Rebaudioside 7.1 higher temperature had to be used. At 300K the resonances in the spectrum of Rebaudioside 7.1 were rather broad, indicating either bad solubility or slow conformational processes. Therefore, the final assignment of all signals was achieved at a sample temperature of 320K.

For each example, various 2D NMR experiments were conducted: COSY, TOCSY (with 40, 50, 60, 70, 80, 90 and 100 ms mixing time), HSQC, HMBC and ROESY (225, 400 ms mixing time) spectra were recorded at 320 K on a Bruker Avance III 600 and 700 MHz spectrometer. The detailed assignment for each example is specified in the example section.

In Examples 4, 5 and 6, the atom numbering of steviol and glucose is as set out in FIGS. 11A and 11B, respectively.

TABLE 15 Description of the sequence listing Nucleic Nucleic acid (CpO acid (CpO for S. for Y. Amino cerevisiae) lipolytica) acid Id* UniProt{circumflex over ( )} Organism SEQ ID NO: SEQ ID NO: SEQ ID CPS_1 Q9FXV9 Lactuca sativa 1 151 NO: 2 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID tCPS_l Q9FXV9 Lactuca sativa 3 152 NO: 4 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID CPS_2 D2X8G0 Picea glauca 5 153 NO: 6 SEQ ID NO: SEQ ID NO: SEQ ID CPS_3 Q45221 Bradyrhizobium 7 154 NO: 8 japonicum SEQ ID NO: SEQ ID NO: SEQ ID KS_1 Q9FXV8 Lactuca sativa 9 155 NO: 10 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID tKS_l Q9FXV8 Lactuca sativa 11 156 NO: 12 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID KS_2 D2X8G1 Picea glauca 13 157 NO: 14 SEQ ID NO: SEQ ID NO: SEQ ID KS_3 Q45222 Bradyrhizobium 15 158 NO: 16 japonicum SEQ ID NO: SEQ ID NO: SEQ ID CPSKS_1 O13284 Phaeosphaeria sp 17 159 NO: 18 SEQ ID NO: SEQ ID NO: SEQ ID CPSKS_2 Q9UVY5 Gibberella fujikuroi 19 160 NO: 20 SEQ ID NO: SEQ ID NO: SEQ ID KO_1 B5MEX5 Lactuca sativa 21 161 NO: 22 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID KO_2 B5MEX6 Lactuca sativa 23 162 NO: 24 (Garden Lettuce) SEQ ID NO: SEQ ID NO: SEQ ID KO_3 B5DBY4 Sphaceloma manihoticola 25 163 NO: 26 SEQ ID NO: SEQ ID NO: SEQ ID KAH_1 Q2HYU7 Artemisia annua 27 164 NO: 28 (Sweet wormwood). SEQ ID NO: SEQ ID NO: SEQ ID KAH_2 B9SBP0 Ricinus communis 29 165 NO: 30 (Castor bean). SEQ ID NO: SEQ ID NO: SEQ ID KAH_3 Q0NZP1 Stevia rebaudiana 31 166 NO: 32 SEQ ID NO: SEQ ID NO: SEQ ID KAH_4 JP2009065886 Arabidopsis thaliana 33 167 NO: 34 (Mouse-ear cress) SEQ ID NO: SEQ ID NO: SEQ ID UGT1_1 A9X3L6 Ixeris dentata var. 35 168 NO: 36 albiflora. SEQ ID NO: SEQ ID NO: SEQ ID UGT1_2 B9SIN2 Ricinus communis 37 169 NO: 38 (Castor bean). SEQ ID NO: SEQ ID NO: SEQ ID UGT3_1 A9X3L7 Ixeris dentata var. 39 170 NO: 40 Albiflora SEQ ID NO: SEQ ID NO: SEQ ID UGT3_2 B9IEM5 Populus trichocarpa 41 171 NO: 42 (Western balsam poplar) SEQ ID NO: SEQ ID NO: SEQ ID UGT3_3 Q9M6E7 Nicotiana tabacum 43 172 NO: 44 SEQ ID NO: SEQ ID NO: SEQ ID UGT3_4 A3E7Y9 Vaccaria hispanica 45 173 NO: 46 SEQ ID NO: SEQ ID NO: SEQ ID UGT3_5 P10249 Streptococcus mutans 47 174 NO: 48 SEQ ID NO: SEQ ID NO: SEQ ID UGT4_1 A4F1T4 Lobelia erinus 49 175 NO: 50 (Edging lobelia) SEQ ID NO: SEQ ID NO: SEQ ID UGT4_2 Q9M052 Arabidopsis thaliana 51 176 NO: 52 (Mouse-ear cress) SEQ ID NO: SEQ ID NO: SEQ ID CPR_1 Q7Z8R1 Gibberella fujikuroi 53 177 NO: 54 SEQ ID NO: SEQ ID NO: SEQ ID CPR_2 Q9SB48 Arabidopsis thaliana 55 178 NO: 56 (Mouse-ear cress) SEQ ID NO: SEQ ID NO: SEQ ID CPR_3 Q9SUM3 Arabidopsis thaliana 57 179 NO: 58 (Mouse-ear cress) SEQ ID NO: SEQ ID NO: SEQ ID CPS_SR O22667 Stevia rebaudiana 59 141 NO: 60 SEQ ID NO: SEQ ID NO: SEQ ID tCPS_SR O22667 Stevia rebaudiana 61 142 NO: 62 SEQ ID NO: SEQ ID NO: SEQ ID KS_SR Q9XEI0 Stevia rebaudiana 63 143 NO: 64 SEQ ID NO: SEQ ID NO: SEQ ID tKS_SR Q9XEI0 Stevia rebaudiana 65 144 NO: 66 SEQ ID NO: SEQ ID NO: SEQ ID KO_SR Q4VCL5 Stevia rebaudiana 67 145 NO: 68 SEQ ID NO: SEQ ID NO: SEQ ID KAH_SR US7927851 Stevia rebaudiana 69 146 NO: 70 SEQ ID NO: SEQ ID NO: SEQ ID UGT1_SR Q6VAB0 Stevia rebaudiana 71 147 NO: 72 SEQ ID NO: SEQ ID NO: SEQ ID UGT3_SR Q6VAA6 Stevia rebaudiana 73 148 NO: 74 SEQ ID NO: SEQ ID NO: SEQ ID UGT4_SR Q6VAB4 Stevia rebaudiana 75 149 NO: 76 SEQ ID NO: SEQ ID NO: SEQ ID CPR_SR Q2I6J8 Stevia rebaudiana 77 150 NO: 78 SEQ ID NO: SEQ ID tHMG1 G2WJY0 Saccharomyces cerevisiae 79 NO: 80 SEQ ID NO: SEQ ID ERG20 E7LW73 Saccharomyces cerevisiae 81 NO: 82 SEQ ID NO: SEQ ID BTS1 E7Q9V5 Saccharomyces cerevisiae 83 NO: 84 SEQ ID NO: SEQ ID NO: SEQ ID KO_Gibfu O94142 Gibberella fujikuroi 85 180 NO: 86 SEQ ID NO: SEQ ID NO: SEQ ID UGT2_1a B3VI56/99% Stevia rebaudiana 87 181 NO: 88 SEQ iD NO: SEQ ID KAH_ASR1 Xxx S. rebaudiana 89 NO: 90 SEQ ID NO: SEQ ID KAH_ASR2 Q0NZP1_STERE S. rebaudiana 91 NO: 92 SEQ ID NO: SEQ ID KAH_AAT Q6NKZ8_ARATH A. thaliana 93 NO: 94 SEQ ID NO: SEQ ID KAH_AVV F6H1G0_VITVI/98% Vitis vinifera 95 NO: 96 SEQ ID NO: SEQ ID KAH_AMT Q2MJ20_MEDTR Medicago truncatula 97 NO: 98 SEQ ID NO: SEQ ID UGT2_1b B3VI56/99% S. rebaudiana 99 NO: 100 SEQ ID NO: SEQ ID UGT2_2 Q53UH5_IPOPU I. purpurea 101 NO: 102 SEQ ID NO: SEQ ID UGT2_3 UGAT_BELPE/99% Bellis perennis 103 NO: 104 SEQ ID NO: SEQ ID UGT2_4 B3VI56 S. rebaudiana 105 NO: 106 SEQ iD NO: SEQ ID UGT2_5 Q6VAA8 S. rebaudiana 107 NO: 108 SEQ ID NO: SEQ ID UGT2_6 Q8LKG3 S. rebaudiana 109 NO: 110 SEQ ID NO: SEQ ID UGT2_7 B9HSH7_POPTR Populus trichocarpa 111 NO: 112 SEQ ID NO: SEQ ID UGT_RD1 Q6VAA3 S. rebaudiana 113 NO: 114 SEQ ID NO: SEQ ID UGT_RD2 Q8H6A4 S. rebaudiana 115 NO: 116 SEQ ID NO: SEQ ID UGT_RD3 Q6VAA4 S. rebaudiana 117 NO: 118 SEQ ID NO: SEQ ID UGT_RD4 Q6VAA5 S. rebaudiana 119 NO: 120 SEQ ID NO: SEQ ID UGT_RD5 Q6VAA7 S. rebaudiana 121 NO: 122 SEQ ID NO: SEQ ID UGT_RD6 Q6VAA8 S. rebaudiana 123 NO: 124 SEQ ID NO: SEQ ID UGT_RD7 Q6VAA9 S. rebaudiana 125 NO: 126 SEQ ID NO: SEQ ID UGT_RD8 Q6VAB1 S. rebaudiana 127 NO: 128 SEQ ID NO: SEQ ID UGT_RD9 Q6VAB2 S. rebaudiana 129 NO: 130 SEQ ID NO: SEQ ID UGT_RD10 Q6VAB3 S. rebaudiana 131 NO: 132 SEQ ID NO: SEQ ID UGT_RD11 B9VVB1 S. rebaudiana 133 NO: 134 SEQ ID NO: SEQ ID UGT_RD12 C7EA09 S. rebaudiana 135 NO: 136 SEQ ID NO: SEQ ID UGT_RD13 Q8LKG3 S. rebaudiana 137 NO: 138 SEQ ID NO: SEQ ID UGT_RD14 B3VI56 S. rebaudiana 139 NO: 140 SEQ ID NO: tCPS 182 SEQ ID NO: tKS 183 SEQ ID NO: CPSKS 184 SEQ ID NO: KAH4 185 SEQ ID NO: KO_Gibfu 186 SEQ ID NO: CPR1 187 SEQ ID NO: CPR3 188 SEQ ID NO: UGT1 189 SEQ ID NO: UGT3 190 SEQ ID NO: UGT4 191 SEQ ID NO: UGT2_1a 192 SEQ ID NO: pTPI 193 SEQ ID NO: gpdT-pGPD 194 SEQ ID NO: pgmT-pTEF 195 SEQ ID NO: pgkT-pPGM 196 SEQ ID NO: LEU2 and 197 flanking sequences SEQ ID NO: vector sequences 198 SEQ ID NO: pENO 199 SEQ ID NO: HPH 200 SEQ ID NO: Sc Eno2.pro 201 SEQ ID NO: Sc Fba1.pro 202 SEQ ID NO: Sc Tef1.pro 203 SEQ ID NO: Sc Pgk1.pro 204 SEQ ID NO: Kl prom 12.pro 205 SEQ ID NO: Ag lox_TEF1.pro 206 SEQ ID NO: Kl prom 6.pro 207 SEQ ID NO: Sc Pma1.pro 208 SEQ ID NO: Sc Vps68.pro 209 SEQ ID NO: Sc Oye2.pro 210 SEQ ID NO: KANMX ORF 211 SEQ ID NO: Adh1.ter 212 SEQ ID NO: Adh2.ter 213 SEQ ID NO: Gmp1.ter 214 SEQ ID NO: Sc Tal1.ter 215 SEQ ID NO: Sc Tpi1.ter 216 SEQ ID NO: Ag Tef1_lox.ter 217 SEQ ID NO: Sc Pdc1.ter 218 SEQ ID NO: Sc Tdh1.ter 219 SEQ ID NO: Sc Eno1.ter 220 SEQ ID NO: Kl prom3.pro 221 SEQ ID NO: Kl prom2.pro 222 SEQ ID NO: Sc PRE3. Pro 223 greyed out ids are truncated and thus a fragment of mentioned UniProt id 

The invention claimed is:
 1. A steviol glycoside having the formula (IV)


2. The steviol glycoside according to claim 1, wherein it is fermentatively produced.
 3. A method for production of a steviol glycoside according to claim 1, which method comprises: providing a recombinant yeast cell comprising recombinant nucleic acid sequences encoding polypeptides comprising the amino acid sequences encoded by: SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 23, SEQ ID NO: 33, SEQ ID NO: 77, SEQ ID NO: 71, SEQ ID NO: 87, SEQ ID NO: 73 and SEQ ID NO: 75; fermenting the recombinant yeast cell in a suitable fermentation medium.
 4. A composition comprising a steviol glycoside according to claim 1 and one or more different steviol glycosides.
 5. A foodstuff, feed and/or beverage which comprises a steviol glycoside according to claim
 1. 6. A product comprising a steviol glycoside according to claim 1 in a sweetener composition or flavor composition.
 7. A product comprising a steviol glycoside according to claim 1 in a foodstuff, feed and/or beverage.
 8. The method of claim 3, further comprising recovering the steviol glycoside from the fermentation medium. 